Method and apparatus for making pneumatic tires



25, 1953 D. J. HINMAN 2,649,891

METHOD AND APPARATUS FOR MAKING PNEUMATIC TIRES Filed June 21, 1951 2Sheets-Sheet l INVENTOR. fld/P/F AVA/M4 Wf y Aug. 25, 1953 D. J, HINMAN2,649,391

METHOD AND APPARATUSFOR} MAKING PNEUMATIC TIRES Filed June 21, 1951 2Sheets-Sheet 2 Patented Aug. 25, 1953 METHOD AND APPARATUS FORIMAKINGPNEUMATIC TIRES .;Dorr "J. :Hinman, Detroit, vMich., ,zassignor toUnited States ,Rubber Company, .New York,

N. Y., a-corporation of New Jersey Application June 21, 1951, SerialNo."2232;681

1 8 Claims. 1

'This' invention relates to a methodz'andrapparatus for making pneumatictires, and more particularly "itrelates to :as'method for preparing :a.raWtire-casing :in generally flat'band form.

xOnefobjeot or the invention is tovprovide an improved method of makingpneumatic 'tires tby molding the greater portion of ?the router rubber'coveringof the tire.

Another obj ect is' the :provisionof a method :of makin :pneumatic tireswhich avoids the necesrsity' for any transverse: splice in the tire.

C'Slilll another object is to "provide a method 'of 'making :pneumatictires which insures :that thetread' will be uniform around thecircumferen'ceof the tire, therby reducing -;or eliminating theznoisefland undesirable ridingrcharacteristics encountered in tires that are notaccurately balanced.

aqfiturther object of 'the' invention is 'the provizsion ofaarmethodfian'd apparatus for assembling aifliire ceasing thatisuparticularly adaptableffor 'subsequent. shaping-and vulcanizing of-the casaingzinmhat formof :vulcanizing press-adapted torreceiveithecasing while still iin' bandfiorm.

".The manner: in which "the invention :accom- :p'lishes theiforegoingobjects;-as well=as additional objects: and iatdvantages, will "be made:manifest fin theltfiollowingdetailed:description ofthe invention, whichislintendd 'to zbewrea'd with reference .itotheiaccompany-ing'sdrawings, wherein:

fEig. s 1 iis alilargely. rschema'tic "perspective view :showing ta:method-:o'f vprepar-ing approximate'ly "\preform'edzportionssof a' tiretread i Figx-ais a sectional elevational viewaof amoldthen-shaped:andvulcanized by suitable means,

ingzpressoonstructed according to the invention,

tshownrzin the open position;

;Fig;3:isa simi;lar yievvlsh'owingithe press in the rclosedeposition;

-;"Fig.-zz4qisvan elevationali'view of a raw the carcass'preparedwincband:iiormz'and having zsidewall ;portion applied thereto;

-F ig.a"iSi a -view :of the open press similar to -Rig. e1, showing -:atire tcarc'ass being inserted tlrerein;

-=a:;tire carcasssin the closed :position TlFig. I7 isanelevationalviewaofia'. completely asesenibledrraw tirercasin'g after 'removalfromithe wmoldingspress pand :fli'igirzs is anaelevationahview :of thecompleted itire.

rA'econdingiz'to itherinvention, :.'the outer rubber covering, or tread,of the tire casing is molded lZillrpDBtiOIls' having :-agenerallycylindricall or eszsentiallyiiflatiband'iiorm so 'that they are adaptedpreferably in "that type of unit 'vulcanizer adapted to receive theassembly in 'band form and containing:anintegrakcuringbag.

.JReferringHto .thedrawing, andrinxparticular to Figs. 2.:an'd13,1;theapparatussshown therein for *carryingout the invention includes :amolding press ih'aving alowerffixed'cylindrical. mold shell I10 securedto"'the.uppersurface ofralowerfframe- :work II of the ?press,:andx acooperating upper movable cylindrical mold shell :t2 ,1 that is securedto the lower surfacezof 'amovableplaten l3 scar- Tied by 'a verticallyreciprocating piston 14 of .a vertical hydraulic mylinder 1.5 secured tothe upper framework i6 of thelpress. vA. removable cylindricalcorermember l'l iszadapted to be disposed within th :hollow interior ofthe mold :shells 0, :12, and-defines "therewith, as indicated iniE'igg3,lower and upper "annular mold cavities 18 'and t9, each having thegeneral shape-of a transaxialihalf of the majorzportionof the outerrubber. coverin :ofrattire casingin the form of a generally fiat band.

The'lo-wer portion 20 of the interior'of theolower zmoldxshell i0 :is ofreduced :diameter -and bears O slidably against a flat portion 12l of"the lower outerssurface'rof the. core I! when the :parts :are broughtinto Jengagement .as :indicated in Fig. 3. :Above the lower portion 20'the interior .of the sshell lll is :provided with a graduall outwardlyenlarged area '22 formingza wall "of the :mold .cavity 'I 8vcorresponding to' the sloping shoulder vpor- :tion'ofa tire tread.Above the-sloping portion 22 there is provided 'onitheiinterior 'ofthe'shell ill a further. enlarged portion 23 of essentially'con- -stantdiametenzforming a -.wall of the cavity "3, corresponding to the:central or road-contacting portion of a tire tread. Above the 'flatportion 2l itheexterior surface of the core I1 is provided with an area'24 that gradually increases in diameter toward the central'horizontalplaneo'f the "core. "When'the =mold parts are in-engagement, thes'lopingsurface 24 o'fthe corell is disposed oppositely to and spaced from thesurface 20 and 2-2 of the shell), thereby-defining the inner 0wall-of'the lower mold cavity H3.

The core l'l-"has a horizontal'fiange'portion 25 extending radiallyoutwardly therefrom at its central plane, and the lower inner surface'26 of thisfiangedefines'the'upper endwall of the'cavity 113 -when themdld is-c1osed. "The radially 'outer U portion 21 of the flange 25 is ofincreased thickness, thereby defining a recess 23 which cooperates witha corresponding recess 29 in the upper outer surface of the shell Ill,the contacting surfaces of the recesses 28, 29 bearing slidably againsteach other when the mold is closed.

The upper mold shell i2 is constructed similarly to the lower mold shellIll, and the upper half of the core ll is constructed similarly to thelower half thereof, as just described.

The surfaces of the mold shell are adapted to receive strips 33 and 3!of rubber stock which are to be molded in the mold cavities I8 and 59into transaxial halves 32 and 33 of the main body of the tire tread. Inorder to facilitate shaping of the strips 30 and 3| into the desiredform with a minimum of distortion, the-strips are prefer ably made inthe general contour of the tire tread which they are intended to form.One method of forming the strips 32 and El, as illustrated in Fig. 1,comprises extruding a continuous length S of rubber stock having thecross sectional shape of the central portion of the tire tread from anextruding device E, and slitting such length longitudinally by means ofa suitably positioned knife 31. The extruded stock is out transverselyat suitable intervals by a skiving knife 38, producing the lengths 3dand 35 which may be spliced into annular form and placed on the surfaceof the core ll as indicated in Fig. 2. Preferably the lengths 3B and 3!are spliced into bands which are slightly undersize in circumferencewith respect to the circumference of the core 11, so that they must bestretched slightly when applied to the core, and thereby clin to andsubstantially conform to the surfaces of the core. The preforms 38, 3|may be made of any suitable vulcanizable rubber stock and may either becomposed entirely of one kind of stock, or may be composed of aplurality of stocks, e. g., they may be composed of a cap stock, thatis, a highly abrasion-resistant tread stock in that portion thatultimately corresponds to the road-contacting surface of the tread,combined with a base stock in that portion that will ultimately bedisposed underneath and to the side of the roadcontacting portion.

Control of the movement of the upper mold half l2 into and out ofengagement with the core I1 and the lower mold half H is effected by aconventional four way valve 34, from which hydraulic fluid lines 35, 36,supplied with hydraulic fluid from a suitable source (not shown), passto each end of the cylinder for actuating the piston mechanism [4 ineither direction.

For circulating a heating or cooling medium through the body of the moldshells during the molding operation, internal passageways 40, 4| areprovided, through which steam or other fluid heating medium, or coolingwater, may be introduced from a suitable source (not shown) throughinlet and outlet connections 42, 43,

In order to make it possible to rotate the core H with respect to themold shells l9, l2 for the purpose of counteracting any shrinkagestresses in the molded forms 32, 33, in the manner described in detailin my copending application Serial No. 232,683, filed of even dateherewith and assigned to the same assignee as the instant application,the outer periphery of the enlarged portion 21 of the flange 25 isprovided with gear teeth 44 that are engaged, when the core is inmolding position within the shells, by a pinion gear 45 driven by asuitable hydraulic motor 46 mounted on the lower frame ll of themachine.

For associating the molded forms 32, 33 with a tire carcass 4'5, meansare provided within the mold shells for supporting a tire carcasstherein in band form in a vertical position. Such means include a lowermovable horizontal bead flange- 48 disposed concentrically of the lowermold shell Ill and mounted on the upper end of a hydraulic pistonmechanism 49 that is adapted to be raised and lowered by means of avertical hydraulic cylinder 59 contained in the base framework ll of themachine, and supplied with hydraulic fluid through lines 5 I, 52controlled by the usual valve 53. The peripheral edge of the bead flange48 on which a head portion 55 of the tire carcass ll is adapted to bemounted, is provided with a recess 55 for receiving the bead in securefrictional engagement with the edge of the flange.

A similar upper horizontal movable bead flange 56 is mounted forvertical movement in the upper mold shell l2 by means of a verticalhydraulic mechanism 5! operating in a cylinder 58 contained in the lowerportion of the interior of the upper piston 14 of the press, andsupplied with hydraulic fluid through lines 59, 6%, controlled by avalve 6 I. The upper bead flange 55 also has a peripheral recess 62 foraccommodating a bead of the tire carcass 41.

For introducing fluid under pressure, usually air, to the interior ofthe carcass il when it is mounted on the flanges 48, 56 to aid inuniting the carcass to the molded portions 32, 33, a fluid inlet line 63passes to the lower end of the hydraulic piston mechanism 49 extendingfrom the lower framework of the machine, into communication with apassageway 64 extending upwardly through the center of the piston t9,and opening into the hollow interior 55 of the carcass.

The operation of the apparatus is as follows:

The formed bands 30, 3| of rubber stock are placed on the upper andlower lateral surfaces of the core piece IT, and the core piece isinterposed between the mold shells I0, I2 While the press is in the openposition, as indicated in Fig. 2. The bands 30, 3! are preferably at asuitable elevated temperature, e. g., 200 F., when they are placed onthe core. Ordinarily, the preforms will retain sufficient heat from theprevious extrusion operation by which they were formed to be at thistemperature. It is also preferable that the core piece be preheated toan elevated temperature, e. g. 200 F. The mold shells l0, l2 are alsopreheated to an elevated temperature, e. g., approximately 250 F., as bycirculating heated fluid through the passages 46, 4|. The core I! islowered into the central opening of the lower mold shell l0, and theupper mold shell I2 is moved downwardly by actuating the hydrauliccontrol valve 34 to motivate the piston mechanism [4 of the upperhydraulic cylinder 15 of the press. The mold core I! carrying the rawrubber bands 30, 3| is thereby enclosed under pressure and at anelevated temperature by the mold shells I0, I2, and under the influenceof such pressure and heat the rubber stock is shaped in the resultingmold cavities l8, l9 into annular bands 32, 33 having the shape oftransaxial halves of the major portion of the outer rubber covering of atire casing. This molding operation produces a flowing and compacting ofthe rubber stock that shapes the stock accurately in the desired form,and removes any isregsularities originally present in the strips Withthe mold in the closed position, cooling fluid is then circulatedthrough the mold passages prising molding transaxial portions of thecentral area of the outer rubber covering of a tire casing in the formof generally flat bands from vulcanizable rubber stock by application ofheat and pressure in an enclosing mold, preparing a raw tire carcass inthe form of a generally flat annular band, applying raw rubber sidewallstrips to the lateral areas of the flat carcass band, applying the saidmolded fiat bands to the central portion of the flat carcass band, andshaping and curing the assembly in annular toroidal form.

2. A method of making pneumatic tires comprising molding a transaxialsection of the outer rubber covering of a tire casing in the form of agenerally flat band from vulcanizable rubber stock by application ofheat and pressure to the stock between an enclosing mold shell and acooperating mold core, removing said mold shell from said core with themolded stock contained in the shell, substituting a raw tire carcass inthe form of a generally flat annular band for said core, pressing saidmold shell containing the molded transaxial section against the fiatcarcass band, applying heat and pressure to unite said molded section tothe fiat carcass band, applying another such complementary transaxialmolded section to the fiat carcass band in the same manner to completelycover the carcass, and shaping and curing the resulting assembly inannular toroidal form.

3. A method of making pneumatic tires comprising preparing anapproximate preform from a vulcanizable rubber stock in the approximateshape of a transaxial section of the outer rubber covering of a tirecasing in the form of a generally flat annular band, subsequentlymolding said form by application of heat and pressure thereto between anenclosing shell and a cooperating mold core, defining between them acavity having the shape of the desired section of the tire casing andhaving the general form of a flat annular band, removing said mold shellfrom said mold core with the molded form contained in the shell,substituting a raw tire carcass in the form of a generally flat annularband for said core, pressing said mold shell containing the molded formagainst the fiat carcass band, applying heat and pressure to unite saidmolded form to the flat carcass band, applying another suchcomplementary form to the flat carcass band in the same manner tocompletely cover the carcass, and shaping and curing the resultingassembly in annular toroidal form.

4. A method of making a pneumatic tire comprising molding a transaxialsection of the central area of the outer rubber covering of a tirecasing in the form of a generally fiat annular band from vulcanizablerubber stock by the application of heat and pressure to the stockbetween an enclosing mold shell and a cooperating mold core, preparing araw tire carcass in the form of a generally fiat annular band, applyingraw rubber side wall strips to the lateral areas of the fiat carcassband, removing said mold shell from the said core with the molded bandcontained in the core, applying to such mold shells containing moldedbands to the flat carcass band to cover the central area thereof withsaid molded bands, uniting said bands to said carcass by application ofheat and pressure and shaping and curing the assembly in annulartoroidal form.

5. A method of making pneumatic tires com prising molding transaxialsections of the outer rubber covering of a tire casing in the form ofgenerally fiat bands from vulcanizable rubber stock by application ofheat and pressure to the stock in an enclosing mold, applying the moldedflat bands to the surface of a raw tire casing in the form of agenerally flat band, applying internal fluid pressure directly to theinterior of the tire carcass to firmly unite the molded bands to theflat carcass band, and thereafter shaping and curing the resultingassembly in annular toroidal form.

6. A method of making pneumatic tires comprising molding a transaxialsection of the outer rubber covering of a tire casing'in the form of agenerally flat band from vulcanizable rubber stock by application ofheat and pressure to the rubber stock between an enclosing mold shelland a cooperating mold core, removing said mold shell from said moldcore with the molded stock contained in the shell, substituting a rawtire carcass in the form of a generally flat annular band for said core,pressing said mold shell containing the molded transaxial sectionagainst the flat carcass band, applying fluid pressure directly to theinterior of the fiat carcass band to unite the carcass to said moldedsection while said section is in a heated state, applying another suchcomplementary transaxial molded section to the flat carcass band in thesame manner to completely cover the carcass, and shaping and curing theresulting assembly in annular toroidal form.

'7. A method of making pneumatic tires comprising molding a transaxialsection of the central area of the outer rubber covering of a tirecasing in the form of a generally flat band from vulcanizable rubberstock by application of heat and pressure to the rubber stock between anenclosing mold shell and a cooperating mold core, preparing a raw tirecarcass in the form of a generally fiat annular band, applying rawrubber side wallstrips to the lateral areas of the fiat carcass band,cooling said molded bands while still retained between said shell andcore, removing said mold shell from said core with the molded bandcontained in the core, applying two such mold shells containing moldedbands to the flat carcass band to cover the central area thereof withsaid molded bands, uniting said bands to said carcass by application ofheat and pressure, andshaping and curing the assembly in annulartoroidal form.

8. A method of making pneumatic tires comprising molding a transaxialsection of the outer rubber covering of a tire casing in the form ofgenerally flat bands from vulcanizable rubber stock by application, ofheat and pressure to the stock between an enclosing mold shell and a cooperating mold core having less adhesion to the stock than the shellhas, removing said mold shell from said mold core with the molded stockcontained in the shell, substituting a raw tire carcass in the form of agenerally flat annular band for said core, pressing said mold shellcontaining the molded transaxial section against the flat carcass band,applying heat and pressure to unite said molded section to the fiatcarcass band, applying another such complementary transaXial moldedsection to the fiat carcass band in the same manner to completely coverthe carcass, and shaping and curing the resulting assembly in annulartoroidal form.

9. A method of making pneumatic tires comprising molding transaxialsections of the central portion of the outer rubber covering of a tirecasing in the form of annular bands from vulcanizable rubber stock byapplication of heat and pressure to the stock between two enclosing mold'shells and} acooperating mold 'c ore, removing-said shells rrom saidcore with the "molded bands contemperature; applying internal? fluidpressureto the interior. of the--carcass= to: press it. firmly againstthe interiors-- surfaces of said bands, to

unite said carcass and bands, the bands being united at the same timealong circumferential lines of splice to each other and to the saidsidewall strips, removing the resulting assembly from the mold shells inband form, and shaping and curing the assembly in annular toroidal form.

10. A method of making pneumatic tires comprising preparing anapproximate preform from vulcanizable rubber stock in the approximateshape of a transaxial section of the central portion of the outer rubbercovering of a tir casing in the form of a generally flat annular band,molding said preform bands by application of heat and pressure theretobetween two enclosing mold shells and a cooperating mold core, removingsaid shells from said core with the molded bands contained in theshells, preparing a raw tire carcass in the form of a flat annular band,applying raw rubber sidewall strips to the lateral zones of the fiatcarcass band, the external diameter of th carcass assembly being lessthan the internal diameter of said molded bands, bringing said shellscontaining the molded bands into engagement with said flat carcass bandat an elevated temperature, applying internal fluid pressure to theinterior of the carcass to press it outwardly against the interiorsurfaces of said bands to unite said carcass and bands, the bands beingunited at the same tim along circumferential lines of splice to eachother and to the said sidewall strips, removing the resulting assemblyfrom the mold shells in band form, and shaping and curing the assemblyin annular toroidal form.

11. Apparatus for making pneumatic tires comprising a mold shell and acooperating mold core defining between them a mold cavity having theshape of a transaxial section of the outer rubber covering of apneumatic tire casing in the form of a generally flat annular band,means for moving said shell into and out of engagement with said core,means for supporting a raw tire carcass in the form of an annular bandwithin said mold shell, and means for moving said supporting means intoand out of said shell,

12. Apparatus for making pneumatic tires comprising a mold shell and acooperating mold core defining between them a mold cavity having theshape of a transaxial section of the outer rubber covering of apneumatic tire casing in the form of a generally flat annular band,means for moving said shell into and out of engagement with said core,means for supporting a raw tire casing in the form of an annular bandwithin said mold shell, means for moving said supporting means into andout of engagement with said shell,-and means for introducing a fluidunder pressure into the interior of a carcass supported on said supporting means.

13. Apparatus for making pneumatic tires comprising a pair of oppositelydisposed mold shells, a cooperating mold core adapted to be disposed erapneumatic tire casing-in: the form of a generally flatiwannular band,-means for moving: said mold sliells into and out of engagement with said"core,- means i'or' suppor-tinga raw-pneumatic tire c'asing in theform-of anannular band within'said "mold shell's and means for moving'saidsupport- "ing-means into-and out of said shells,

' 14.: Apparatus for makingpneumatictires' com- :prising aipa'i'lll'OfOppOSitehF disposed mold shells, a cooperating mold core :adapted' to bedisposed between said shells, said mold and core defining between themmold cavities having the shape of transaxial sections of the outerrubber covering of a pneumatic tire casing in the form of a generallyflat annular band, means for moving said mold shells into and out ofengagement with said core, means for supporting a raw pneumatic tirecasing in the form of an annular band within said mold shells, means formoving said supporting means into and out of said shells, and means forintroducing a fluid under pressure into the interior of a carcasssupported on said supporting means.

15. Apparatus for making pneumatic tires comprising a mold shell and acooperating mold core defining between them a mold cavity having theshape of a transaxial section of the outer rubber covering of apneumatic tire casing in the form of a generally fiat annular band,means for moving said shell into and out of engagement with said core, aflange within said shell, and movable axially with respect to saidshell, adapted to engage frictionally along its marginal edge a bead ofa raw pneumatic tire casing in the form of an annular band, and meansfor moving said flange into and out of said shell.

16. Apparatus for making pneumatic tires comprising a pair of hollowmold shells, a cooperating mold core adapted to be disposed between saidshells, said shells and core defining mold cavities having the shape ofa transaxial section of the outer rubber covering of a pneumatic tirecasing in the form of a generally flat annular band, means for movingsaid shells into and out of engagement with said core, flanges disposedwithin each of said shells, and movable axially with respect to saidshells, for supporting a pneumatic tire casing in annular band formwithin said shells, and means for moving said flanges into and out ofsaid shells.

1'7. Apparatus for making pneumatic tires comprising a pair of hollowmold shells, a cooperating mold core adapted to be disposed between saidshells, said shells and core defining mold cavities having the shape ofa transaxial section of the outer rubber covering of a pneumatic tirecasing in the form of a generally flat annular band, means for movingsaid shells into and out of engagement with said core, flanges disposedwithin each of said shells, and movable axially with respect to saidshells, for supporting a pneumatic tire casing in annular band formwithin said shells, means for moving said flanges into and out of saidshells and means for introducing a fluid under pressure into theinterior of a carcass supported on said flanges.

18. Apparatus for making pneumatic tires comprising a, pair of hollowmold shells, a cooperating mold core adapted to be disposed between saidshells, said shells and core defining mold cavities having the shape ofa transaxial section of the outer rubber covering of a pneumatic tirecasing in the form of a generally flat annular band, means for movingsaid shells into and out of engagement with said core, flanges disposedwithin each of said shells, and movable axially with respect to saidshells, for supporting a pneumatic tire casing in annular band formwithin said shells, means for moving said flanges into and out of saidshells, and means for introducing a fluid under pressure into theinterior of a carcass supported on said flanges, the interior .walls ofthe mold cavities defined by said core sloping gradually outwardlytoward the central plane of the core to provide outwardly sloping DORRJ. HINMAN.

References Cited in the file of this patent UNITED STATES PATENTS 10Number Name Date 2,476,884 Maynard July 19, 194 9 2,497,226 NcNeill Feb.14, 1950 2,569,935 Leguillon et a1. Oct. 2, 1951

